Improve player nametag rendering

[domdomegg]

The current player nametag is rendered as black 50pt Arial text on a transparent 500×100 canvas with text packed to one corner. The sprite scales the result, so the aspect ratio is wrong and the text reads as a horizontally-squashed black blob hovering above the player — at distance it's effectively invisible against any non-light background.

This PR replaces it with a vanilla-MC-style nametag:

• White text with a soft drop shadow on a translucent black background.
• Canvas sized exactly to the measured text + padding, so the sprite's aspect ratio is correct and the text doesn't squash.
• 80px sans-serif rendered with linear filtering so the tag stays legible at any distance.
• depthTest: false so the tag is visible even when partially occluded by the player or terrain (matches vanilla).

Before / after

Both bots in spectator mode at fixed positions; observer (camera) at the same coords for each pair.

	before	after
near (~2 blocks)
mid (~5 blocks)
far (~9 blocks)

[zardoy]

you should include a better set of font-family defaults something like minecraft,mojangles,monospace (or sans-serif) and maybe making this option customizable

[domdomegg]

Good call — done. Switched the nametag font from a bare sans-serif to a fallback stack minecraft, mojangles, monospace, so it picks up a real Minecraft font if one's installed and degrades gracefully to monospace otherwise. (Also hoisted it into a single font const so the measure and draw contexts can't drift apart.)

I left the font non-customizable for now — happy to add an option to override it if there's a concrete need, but erring towards fewer knobs to keep things simple unless someone actually wants it.

[extremeheat]

No need for monospace but otherwise looks good beyond the nit that a new canvas is unnecessarily created for every call here

[domdomegg]

Thanks! Dropped monospace from the fallback — now minecraft, mojangles, sans-serif.

Good catch on the per-call measuring canvas too. I've left it as-is for this PR to keep it focused on the nametag rendering, but happy to hoist a shared 1×1 measuring canvas into a module-level const in a quick follow-up if you'd prefer it in here.